As columbella duclosiana:
Shell small, with six slightly rounded whorls, rather short, smooth and shining; outer lip with a slightly thickened varix, feebly notched above, smooth within; base of the shell but little contracted; columella deeply excavated about at the middle; the few revolving ridges at the base are continued over it. Color white, or yellowish white, sometimes maculated near the suture.
Length, 3; diameter, 1.5 mm.

Astyris lunata (Say, 1826) Lunar Dovesnail
Distribution: Massachusetts to Florida to Texas to Brazil; Bermuda. Size: 6 mm
Description: Color variable, typically tannish-white with axially oriented irregular, zigzag brownish to purplish bands with a brown apex; shape broadly ovate, conic; sculpture smooth; convex whorls, impressed sutures; arched columella not markedly denticulate; outer area of aperture at base with spiral grooves; inner area of outer lip thin and smooth.
Habitat: Low-tide line on grass; rocks in bays at depths from 0 to 115 m (377 ft). Remarks: Similar to A. multilineata; however, A. lunatus is broader basally, the outer lip is not noticeably denticulate, and coloration is not as vibrant. See Rehder (1981); Odé (1983c). Synonym: Mitrella lunata Say, 1826.